Scanned images of ionograms collected by the ISIS Topside Sounder satellites 
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This directory contains JPG and PNG images of ISIS topside sounder ionograms that were 
scanned from the original rolls of microfilm. The 42 rolls of microfilm were received 
from Gordon James (Canada) and include 1 roll from Alouette 1, 1 roll from Alouette 2, 
1 roll from ISIS 1, 2 rolls from the ground-based Resolute Bay ionosonde, and 35 rolls 
from ISIS 2. These images are the result of  a NASA-HDEE data upgrade grant to Space 
Environment Corporation (Vince Eccles, PI).


The data are stored in the following subdirectories:

ORIGINAL_SCANS_JPG (155 GB): Original scanned images in JPG format from all of the 
microfilms; orientations and black/white levels vary.  Each subdirectory contains the 
images from one roll of microfilm. The sub-directory names are generally the satellite 
abbreviation (AL1=Alouette 1, IS2=ISIS2, etc.), the ground station code (43=Resolute 
Bay), and then the film number (e.g., IS2_43-182 contains the images from ISIS-2 for 
Resolute Bay from roll #182).  The exceptions are from the first test scans, where 
SNV_B1 images are from the Resolute Bay ionosonde and the SNV_B images are from ISIS2.
The scans are fixed-size images, so the ionogram frames tend to be broken arbitrarily 
between images.  The SEC group developed a tool to put the images together and break 
out the frames, as demonstrated in the IONOGRAM_EVENTB_PNG directory for Event B. 

REDUCED_SIZE_PNG (99 GB): Reduced size images in a standard orientation in PNG format, 
used for further analysis. Each sub-directory contains the images from one roll of film 
and uses the same naming convention as in the ORIGINAL_SCANS_JPG directory. Each PNG 
file is accompanied by a TXT file with two columns of numbers representing the average 
gray level (0=black, 255=white) for each horizontal line of the frame; these values are 
used to determine where the data portion of each frame is located.

IONOGRAMS_EVENTB_PNG (1.2 GB): Includes complete ionogram frames in PNG format for Event 
B (Days 161-177 of 1972) in sub-directories IS2_43-098, SNV_B-43_095, SNV_B-43_096, 
SNV_B-43_097. The PLOTS directory includes the ground track for each Resolute Bay 
ISIS-2 pass in geomagnetic coordinates, obtained from the "worldmap" program output.  

NOTES (3.9 MB): Specific notes regarding each roll of film. Subdirectory naming is 
the same as in ORIGINAL_SCANS_JPG.
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Data Contact: Don Rice (rice at spacenv.com)
SPDF Contact: Dieter Bilitza (dieter.bilitza-1 at nasa.gov)